CN115832180B - Secondary battery, battery module, battery pack and power utilization device thereof - Google Patents

Secondary battery, battery module, battery pack and power utilization device thereof Download PDF

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CN115832180B
CN115832180B CN202210007505.5A CN202210007505A CN115832180B CN 115832180 B CN115832180 B CN 115832180B CN 202210007505 A CN202210007505 A CN 202210007505A CN 115832180 B CN115832180 B CN 115832180B
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secondary battery
antimony
fluorine
electrolyte
coating
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CN115832180A (en
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杨成龙
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Contemporary Amperex Technology Co Ltd
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Contemporary Amperex Technology Co Ltd
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Priority to PCT/CN2022/137547 priority patent/WO2023130888A1/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0567—Liquid materials characterised by the additives
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0568—Liquid materials characterised by the solutes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

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  • Chemical & Material Sciences (AREA)
  • General Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Inorganic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Battery Electrode And Active Subsutance (AREA)
  • Secondary Cells (AREA)

Abstract

The application provides a secondary battery, a battery module, a battery pack and an electric device thereof. The secondary battery comprises a negative electrode plate and electrolyte, wherein the negative electrode plate comprises a current collector, an active material layer and a coating, the active material layer is positioned between the current collector and the coating, and the coating comprises particles containing antimony elements; the electrolyte contains lithium salt and a fluorine-containing additive, wherein the fluorine-containing additive is a fluorine-containing ester single-ring compound; wherein the molar ratio of the antimony element to the fluorine-containing additive is 1:30-9:1, alternatively 1.5:10-9:10. In this application, through using above-mentioned secondary cell, help forming the SEI membrane that the LiF content is high at the negative pole piece, can effectively prevent the co-embedding of solvent molecule, avoid the destruction of solvent molecule co-embedding to the negative pole material, when having reduced the decomposition of solvent in the electrolyte, can improve cycle performance, extension secondary cell's life-span.

Description

Secondary battery, battery module, battery pack and power utilization device thereof
Technical Field
The present disclosure relates to the field of battery technologies, and in particular, to a secondary battery, a battery module, a battery pack, and an electrical apparatus thereof.
Background
In recent years, with increasing demands for clean energy, secondary batteries have been widely used in energy storage power systems such as hydraulic power, thermal power, wind power and solar power stations, and in various fields such as electric tools, military equipment, aerospace and the like. As the application field of the secondary battery is greatly expanded, higher demands are also put on the performance thereof.
In order to further improve the endurance and service life of the secondary battery, improve the user experience, and how to improve the cycle performance and service life of the secondary battery, this has become a technical problem to be solved.
Disclosure of Invention
Technical problem to be solved by the present application
The present application has been made in view of the above problems, and an object thereof is to provide a secondary battery, a battery module, a battery pack, and an electric device thereof, each of which has a long endurance and service life.
Technical scheme for solving problems
In order to achieve the above object, the present application provides a secondary battery, a battery module, a battery pack, and an electric device thereof.
Secondary battery
A first aspect of the present application provides a secondary battery comprising a negative electrode tab and an electrolyte; the negative electrode plate comprises a current collector, an active material layer and a coating, wherein the active material layer is positioned between the current collector and the coating, and the coating comprises particles containing antimony elements; the electrolyte contains lithium salt and a fluorine-containing additive, wherein the fluorine-containing additive is a fluorine-containing ester single-ring compound; wherein the molar ratio of the antimony element to the fluorine-containing additive is 1:30-9:1, alternatively 1.5:10-9:10.
In this application, will contain the coating of antimony element and set up in the surface on negative electrode active material layer, at first, but greatly reduced pole piece processing degree of difficulty avoids the negative electrode active material thick liquids subsides etc. that bring because of the material mismatch to the poor condition of thick liquids stability. Meanwhile, when the negative electrode plate is applied to electrolyte containing lithium salt and fluorine-containing additive, the antimony element on the surface of the negative electrode plate has higher concentration and can quickly react with free lithium ions ionized from the lithium salt in the electrolyte to form Li on the surface of the negative electrode plate 3 The film layer with higher Sb content is beneficial to promoting the formation of the SEI film with higher stability on the surface of the negative electrode plate. When the secondary battery contains the negative electrode plate and the electrolyte, the co-intercalation of solvent molecules in the negative electrode plate can be effectively inhibited, and the damage to electrode materials caused by the co-intercalation of the solvent molecules is reduced; meanwhile, the decomposition of the electrolyte solvent is reduced, so that the cycle performance of the secondary battery is improved, and the service life of the secondary battery is prolonged.
In the present application, esters containing fluorine are selectedThe single-ring compound is used as a fluorine-containing additive, and compared with a fluorine-containing ester compound with a larger number of rings, the single-ring compound has lower steric hindrance with Li 3 The bonding energy of Sb is stronger, is favorable for being adsorbed on the surface of the negative electrode plate in preference to solvent molecules, and is decomposed to form an SEI film with higher stability.
The present application also ensures the formation of Li without affecting other components of the battery system by limiting the molar ratio of the antimony element to the fluorine-containing additive in the secondary battery 3 The good adsorption relation between Sb and fluorine-containing additives can prevent the problems of too little solvent, too much active ion loss, uneven SEI film coating and the like.
In any embodiment, the particles containing antimony element are at least one of elemental antimony, antimony oxide and antimony trifluoride, and optionally at least one of elemental antimony, antimony trioxide and antimony trifluoride. In the present application, by using at least one of an elemental antimony, an oxide of antimony, and antimony trifluoride as the coating layer, a lithium ion in the electrolyte can be reacted to produce a lithium-containing material 3 And the Sb film layer is further adsorbed with fluorine-containing additives to promote the decomposition of the fluorine-containing additives to form the SEI film with high LiF content. By Sb 2 O 3 For example, the reaction formula with lithium ions in the electrolyte is:
Sb 2 O 3 +6Li + →2Sb 3+ +3Li 2 O、
3Li + +Sb→Li 3 Sb、
SbF 3 +3Li + →3LiF+Sb 3+ 。
therefore, the co-intercalation of solvent molecules can be effectively prevented, damage to electrode materials caused by the co-intercalation of the solvent molecules is avoided, the cycle performance of the secondary battery is improved, and the service life of the secondary battery is prolonged.
In any embodiment, the volume average particle diameter Dv50 of the antimony element-containing particles is 10nm to 1000nm, alternatively 50nm to 300nm. According to the method, the particles containing the antimony element within the range of the proper volume average particle diameter Dv50 are selected, so that the condition of overlarge particle diameter can be effectively prevented, and the improvement effect of the secondary battery cycle performance is ensured.
In any embodiment, the thickness of the coating is 200nm to 5000nm, alternatively 500nm to 3000nm. The present application can improve the cycle performance of the secondary battery without affecting the capacity and extend the service life of the secondary battery by controlling the thickness of the coating layer within a proper range.
In any embodiment, the mass percent of the coating layer is 2% to 30%, alternatively 5% to 20%, based on 100% of the total mass of the coating layer and the active material layer. According to the preparation method, the mass percentage of the coating is controlled within a proper range, so that on one hand, a uniform SEI film with a stable structure can be formed on the surface of the negative electrode plate, and the protection effect on the negative electrode material is good; meanwhile, the consumption of active lithium is low, and the battery capacity is guaranteed, so that the cycle performance of the secondary battery can be improved, and the service life of the secondary battery is prolonged.
In any embodiment, the fluorine-containing additive comprises at least one of fluoroethylene carbonate, phenyl trifluoroacetate, allyltris (2, 2-trifluoroethyl) carbonate, optionally fluoroethylene carbonate or phenyl trifluoroacetate. When the fluorine-containing additive is selected, the substance and Li are compared with other solvent molecules 3 Sb has stronger binding energy and stronger attraction to each other, and can be preferentially adsorbed to Li 3 And decomposing the surface of the Sb film layer to generate the SEI film with higher and stable LiF content. LiF is an inorganic compound, and has better stability than other organic components in the SEI film. When the content of LiF in the SEI film is higher, the film strength can be improved, cracking of the SEI film caused by expansion is resisted, co-embedding of solvent molecules is effectively prevented, and damage to electrode materials caused by co-embedding of solvent molecules is avoided. Therefore, the fluorine-containing additive with the range can generate the SEI film with higher and stable LiF content, can effectively prevent the co-intercalation of solvent molecules, avoid the damage to electrode materials caused by the co-intercalation of the solvent molecules, and further improve the cycle performance and the service life of the secondary battery.
In any embodiment, the fluorine-containing additive is present in an amount of 0.5% to 20%, alternatively 2% to 10%, by mass based on the total mass of the electrolyte. According to the preparation method, the mass percentage of the fluorine-containing additive is controlled within a proper range, so that on one hand, the low consumption of solvent for forming the SEI film can be ensured, the decomposition of the solvent is prevented, the battery capacity is ensured, and the use of the full life cycle is satisfied; meanwhile, the solvent in the electrolyte can be ensured to be in a proper ratio, and the conditions of an electrolyte system, solubility, viscosity and the like are ensured to be in a good state, so that the cycle performance of the secondary battery is improved, and the service life of the secondary battery is prolonged.
In any embodiment, the electrolyte comprises a lithium salt having a molar concentration of 0.7M to 1.5M.
In any embodiment, the active material layer contains at least one of graphite, hard carbon, soft carbon, lithium titanate, tin-based material, nickel-based material, and alloy material.
A second aspect of the present application provides a battery module comprising the secondary battery of the first aspect of the present application. The battery module has good cycle performance and long service life.
A third aspect of the present application provides a battery pack comprising the battery module of the second aspect of the present application. The battery pack has good cycle performance and long service life.
A fourth aspect of the present application provides an electric device comprising at least one selected from the secondary battery of the first aspect of the present application, the battery module of the second aspect of the present application, or the battery pack of the third aspect of the present application. The electric device has good cycle performance and long service life.
Advantageous effects
The application provides a secondary battery, which comprises a negative electrode plate and electrolyte, wherein the negative electrode plate comprises a current collector, an active material layer and a coating, the active material layer is positioned between the current collector and the coating, and the coating comprises particles containing antimony elements; the electrolyte contains lithium salt and fluorine-containing additive The fluorine-containing additive is a fluorine-containing ester single-ring compound; wherein the molar ratio of the antimony element to the fluorine-containing additive is 1:30-9:1, alternatively 1.5:10-9:10. In the present application, by using the secondary battery, li-containing materials can be formed on the surface of the negative electrode tab after charging 3 The Sb film layer is decomposed by preferentially adsorbing the fluorine-containing additive in the electrolyte to form an SEI film with high LiF content, so that co-intercalation of solvent molecules can be effectively prevented, damage to a negative electrode material caused by co-intercalation of the solvent molecules is avoided, the cycle performance can be improved while the decomposition of the solvent in the electrolyte is reduced, and the service life of the secondary battery is prolonged.
Drawings
Fig. 1 is a schematic view of a negative electrode tab according to an embodiment of the present application.
Fig. 2 is a schematic view of a secondary battery according to an embodiment of the present application.
Fig. 3 is an exploded view of the secondary battery according to an embodiment of the present application shown in fig. 2.
Fig. 4 is a schematic view of a battery module according to an embodiment of the present application.
Fig. 5 is a schematic view of a battery pack according to an embodiment of the present application.
Fig. 6 is an exploded view of the battery pack of the embodiment of the present application shown in fig. 5.
Fig. 7 is a schematic view of an electric device in which the secondary battery according to an embodiment of the present application is used as a power source.
Reference numerals illustrate:
1, a battery pack; 2, upper box body; 3, lower box body; 4, a battery module; 5 a secondary battery; 51 a housing; 52 electrode assembly; 53 top cap assembly.
Detailed Description
Hereinafter, embodiments of the secondary battery, the battery module, the battery pack, and the power consumption device of the present application are specifically disclosed with reference to the accompanying drawings as appropriate. However, unnecessary detailed description may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions of the actual same structure may be omitted. This is to avoid that the following description becomes unnecessarily lengthy, facilitating the understanding of those skilled in the art. Furthermore, the drawings and the following description are provided for a full understanding of the present application by those skilled in the art, and are not intended to limit the subject matter recited in the claims.
The "range" disclosed herein is defined in terms of lower and upper limits, with a given range being defined by the selection of a lower and an upper limit, the selected lower and upper limits defining the boundaries of the particular range. Ranges that are defined in this way can be inclusive or exclusive of the endpoints, and any combination can be made, i.e., any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that ranges of 60-110 and 80-120 are also contemplated. Furthermore, if the minimum range values 1 and 2 are listed, and if the maximum range values 3,4 and 5 are listed, the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise indicated, the numerical range "a-b" represents a shorthand representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been listed throughout, and "0-5" is simply a shorthand representation of a combination of these values. When a certain parameter is expressed as an integer of 2 or more, it is disclosed that the parameter is, for example, an integer of 2, 3,4, 5, 6, 7, 8, 9, 10, 11, 12 or the like.
All embodiments and alternative embodiments of the present application may be combined with each other to form new solutions, unless specifically stated otherwise.
All technical features and optional technical features of the present application may be combined with each other to form new technical solutions, unless specified otherwise.
All steps of the present application may be performed sequentially or randomly, preferably sequentially, unless otherwise indicated. For example, the method comprises steps (a) and (b), meaning that the method may comprise steps (a) and (b) performed sequentially, or may comprise steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), may include steps (a), (c) and (b), may include steps (c), (a) and (b), and the like.
Reference herein to "comprising" and "including" means open ended, as well as closed ended, unless otherwise noted. For example, the terms "comprising" and "comprises" may mean that other components not listed may be included or included, or that only listed components may be included or included.
The term "or" is inclusive in this application, unless otherwise specified. For example, the phrase "a or B" means "a, B, or both a and B. More specifically, either of the following conditions satisfies the condition "a or B": a is true (or present) and B is false (or absent); a is false (or absent) and B is true (or present); or both A and B are true (or present).
The inventor finds that the secondary battery, especially at the position of the negative electrode plate, has the problems of co-embedding of solvent molecules and excessive decomposition of the solvent, and is an important influencing factor for restricting the cycle performance and the service life of the secondary battery. According to the inventor, the surface of the negative electrode plate is provided with the coating containing the antimony element substance, and meanwhile, the special additive is added into the electrolyte, so that the cycle performance of the secondary battery can be effectively improved, and the service life of the secondary battery can be prolonged.
Based on this, a first embodiment of the present application provides a secondary battery including a negative electrode tab and an electrolyte; the negative electrode plate comprises a current collector, an active material layer and a coating, wherein the active material layer is positioned between the current collector and the coating, and the coating comprises particles containing antimony elements; the electrolyte contains lithium salt and a fluorine-containing additive, wherein the fluorine-containing additive is a fluorine-containing ester single-ring compound; wherein the molar ratio of the antimony element to the fluorine-containing additive is 1:30-9:1, alternatively 1.5:10-9:10.
As shown in fig. 1, in the present application, the active material layer is disposed between the current collector and the coating layer, and the negative electrode sheet is applied to an electric device containing a lithium salt and a fluorine-containing additiveIn a secondary battery for electrolyte dissolution. In the process of charging the secondary battery, the lithium salt in the electrolyte can ionize to form free lithium ions, which can react with antimony element in the negative electrode plate to form lithium 3 A film layer of Sb. When solvent molecules in the electrolyte and the fluorine-containing ester monocycle compound are simultaneously diffused to the surface of the negative electrode plate, relative to other solvent molecules in the electrolyte, the fluorine-containing ester monocycle compound and Li on the surface of the negative electrode plate 3 Sb has stronger binding energy and stronger attraction force to each other and can be preferentially adsorbed to Li 3 The surface of the Sb film layer and promotes the decomposition of the fluorine-containing additive to generate a solid electrolyte interface film (SEI film) which is stable and has LiF as a main component. In the SEI film, liF is an inorganic compound, and compared with organic components in other SEI films, the SEI film has better stability. When the content of LiF in the SEI film is higher, the film strength can be improved, the SEI film is prevented from cracking caused by expansion, the co-embedding of solvent molecules is effectively prevented, the damage to electrode materials caused by the co-embedding of the solvent molecules is avoided, meanwhile, the decomposition of electrolyte solvents is reduced, the cycle performance of the secondary battery is improved, and the service life of the secondary battery is prolonged.
In the application, the fluorine-containing ester single-ring compound is selected as the fluorine-containing additive, and compared with the fluorine-containing ester compound with a large number of rings, the fluorine-containing ester single-ring compound has lower steric hindrance and is more stable than Li 3 The bonding energy of Sb is stronger, is favorable for being adsorbed on the surface of the negative electrode plate in preference to solvent molecules, and is decomposed to form an SEI film with higher stability. The binding energy refers to the free energy of the binding reaction of two substances, and the smaller the binding energy value is, the easier the two substances are bound.
The secondary battery provided by the application can meet the molar ratio of the antimony element and the fluorine-containing additive in an initial state, particularly in the state of being charged and discharged for less than 10 cycles. After 1000 cycles of charge and discharge, the molar ratio of the two can be kept in the range of 1:5-40:1, alternatively 1:2.5-4:1, because the fluorine-containing additive is consumed in the initial film forming and the cycle process. By limiting the molar ratio of the antimony element to the fluorine-containing additive in the secondary battery, the secondary battery can be obtainedEnsure that Li is formed under the condition of not affecting other components of the battery system 3 The good adsorption relation between Sb and fluorine-containing additives can prevent the problems of excessive consumption of solvents, excessive loss of active ions, uneven coating of SEI films and the like.
In addition, in the application, the coating of the negative electrode plate is directly coated on the surface of the negative electrode active material layer, which is far away from one side of the current collector, compared with the case that the coating material is directly added into the negative electrode active material slurry, the application can greatly improve the processability of the negative electrode plate and avoid the condition that the slurry stability is reduced, such as the sedimentation of the negative electrode plate slurry; specifically, since the particles containing antimony element are easily hydrolyzed, and the anode active material slurry is usually an aqueous slurry, if directly added to the anode active material slurry, a slurry stabilizer or the like needs to be added during the slurry processing, which increases the complexity of the slurry processing. In the application, the negative electrode plate can be simply and rapidly manufactured, and is beneficial to mass production.
In this application, the content of antimony element and the content of fluorine-containing additive can be tested using methods well known in the art. By way of example, the content of antimony element may be tested using an inductively coupled plasma spectrometer (ICP), such as an ICP-3000 instrument from Tianrui corporation; the content of the fluorine-containing additive can be obtained by GC test, for example, by using an instrument such as GC-2014C of Shimadzu corporation. And calculating to obtain the ratio of the two.
In some embodiments, the particles containing elemental antimony are at least one of elemental antimony, oxides of antimony, antimony trifluoride, optionally at least one of elemental antimony, antimony trioxide, antimony trifluoride.
In the present application, by using at least one of an elemental antimony, an oxide of antimony, and antimony trifluoride as the coating layer, a lithium ion in the electrolyte can be reacted to produce a lithium-containing material 3 And the Sb film layer is further adsorbed with fluorine-containing additives to promote the decomposition of the fluorine-containing additives to form the SEI film with high LiF content. By Sb 2 O 3 For example, the reaction formula with lithium ions in the electrolyte is:
Sb 2 O 3 +6Li + →2Sb 3+ +3Li 2 O、
3Li + +Sb→Li 3 Sb、
SbF 3 +3Li + →3LiF+Sb 3+ 。
therefore, the co-intercalation of solvent molecules can be effectively prevented, damage to electrode materials caused by the co-intercalation of the solvent molecules is avoided, the cycle performance of the secondary battery is improved, and the service life of the secondary battery is prolonged.
In some embodiments, the volume average particle diameter Dv50 of the antimony element-containing particles is from 10nm to 1000nm, alternatively from 50nm to 300nm. When the volume average particle diameter Dv of the particles is 50 hours, the number of layers of the particles in the slurry is larger, and the effective coverage area of the particles is also larger. Therefore, the particle containing antimony in the appropriate volume average particle diameter Dv50 can effectively prevent the condition of overlarge particle diameter and ensure the improvement effect of the secondary battery cycle performance.
In the present application, the volume average particle diameter Dv50 of the antimony element-containing particles can be measured by a method known in the art. By way of example, characterization tests may be performed using a Markov laser particle sizer, such as a Malvern Mastersizer-3000 or the like.
In some embodiments, the thickness of the coating is 200nm to 5000nm, alternatively 500nm to 3000nm. Meanwhile, the thickness of the coating is preferably larger than the thickness of the particles, otherwise, the problems of particle scratch and the like are easy to occur. The present application can improve the cycle performance of the secondary battery without affecting the capacity and extend the service life of the secondary battery by controlling the thickness of the coating layer within a proper range.
In this application, the thickness of the coating may be tested using methods well known in the art. By way of example, a Transmission Electron Microscope (TEM) may be used for characterization testing, such as with an instrument from JEOL corporation, JEM-2100F, or the like.
In some embodiments, the coating layer is 2% to 30%, alternatively 5% to 20% by mass based on 100% by mass of the total mass of the coating layer and the active material layer.
Therefore, the mass percentage of the coating is controlled within a proper range, so that on one hand, a uniform SEI film with a stable structure can be formed on the surface of the negative electrode plate, and the protective effect on the negative electrode material is good; meanwhile, the consumption of active lithium is low, and the battery capacity is guaranteed, so that the cycle performance of the secondary battery can be improved, and the service life of the secondary battery is prolonged.
In some embodiments, the fluorine-containing additive includes at least one of fluoroethylene carbonate, phenyl trifluoroacetate, allyltris (2, 2-trifluoroethyl) carbonate, optionally fluoroethylene carbonate or phenyl trifluoroacetate.
When the fluorine-containing additive is selected, the substance and Li are compared with other solvent molecules 3 Sb has stronger binding energy and stronger attraction to each other, and can be preferentially adsorbed to Li 3 And decomposing the surface of the Sb film layer to generate the SEI film with higher and stable LiF content. LiF is an inorganic compound, and has better stability than other organic components in the SEI film. When the content of LiF in the SEI film is higher, the film strength can be improved, cracking of the SEI film caused by expansion is resisted, co-embedding of solvent molecules is effectively prevented, and damage to electrode materials caused by co-embedding of solvent molecules is avoided. Therefore, the fluorine-containing additive with the range can generate the SEI film with higher and stable LiF content, can effectively prevent the co-intercalation of solvent molecules, avoid the damage to electrode materials caused by the co-intercalation of the solvent molecules, and further improve the cycle performance and the service life of the secondary battery.
In some embodiments, the fluorine-containing additive is present in an amount of 0.5% to 20%, alternatively 2% to 10%, by mass based on the total mass of the electrolyte. The secondary battery provided by the application can meet the mass percentage range in an initial state, especially in 10 cycles of charge and discharge.
Therefore, the fluorine-containing additive is controlled within a proper range in percentage by mass, so that on one hand, the low consumption of solvent for forming an SEI film can be ensured, the decomposition of the solvent is prevented, the battery capacity is ensured, and the use of the full life cycle is satisfied; meanwhile, the solvent in the electrolyte can be ensured to be in a proper ratio, and the conditions of an electrolyte system, solubility, viscosity and the like are ensured to be in a good state, so that the cycle performance of the secondary battery is improved, and the service life of the secondary battery is prolonged.
In some embodiments, the molar concentration of the lithium salt in the electrolyte is 0.7M to 1.5M.
In some embodiments, the active material layer may employ a negative active material for a battery, which is well known in the art. As an example, the active material layer may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, tin-based materials, nickel-based materials, lithium titanate, alloy materials, and the like. The alloy material may be selected from a silicon-based material, which may be selected from at least one of elemental silicon, a silicon oxygen compound, a silicon carbon compound, a silicon nitrogen compound, and a silicon alloy. The tin-based material may be at least one selected from elemental tin, tin oxide, and tin alloys. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery anode active material may be used as an active material layer. These materials may be used alone or in combination of two or more.
In some embodiments, the negative electrode tab further includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, the negative electrode film layer including the negative electrode active material. As an example, the anode current collector has two surfaces opposing in its own thickness direction, and the anode film layer is provided on either one or both of the two surfaces opposing the anode current collector.
In some embodiments, the negative electrode current collector may employ a metal foil or a composite current collector. For example, as the metal foil, copper foil may be used. The composite current collector may include a polymeric material base layer and a metal layer formed on at least one surface of the polymeric material base material. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel alloy, titanium alloy, silver alloy, etc.) on a polymer material substrate (e.g., a substrate of PP, PET, PBT, PS, PE, etc.).
In some embodiments, the negative electrode film layer further optionally includes a binder. The binder may be at least one selected from Styrene Butadiene Rubber (SBR), polyacrylic acid (PAA), sodium Polyacrylate (PAAs), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium Alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).
In some embodiments, the negative electrode film layer further optionally includes a conductive agent. The conductive agent is at least one selected from superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
In some embodiments, the negative electrode film layer may optionally further include other adjuvants, such as thickening agents (e.g., sodium carboxymethyl cellulose (CMC-Na)), and the like.
In some embodiments, the negative electrode sheet may be prepared by:
providing slurry of particles containing antimony elements, coating the slurry on at least one surface of a negative electrode active material layer, and drying, cold pressing and other steps to obtain the negative electrode plate.
In the application, the preparation method of the negative electrode plate can be used for simply and easily preparing the negative electrode plate, and has the advantages of low energy consumption and low cost; in addition, by the above method, the active material layer may be provided between the current collector and the coating layer, and thus, a negative electrode sheet conforming to the conditions of the present application may be obtained.
In some embodiments, the antimony element-containing particles are at least one of elemental antimony, oxides of antimony, antimony trifluoride; the active material layer contains at least one of graphite, hard carbon, soft carbon, lithium titanate, tin-based material, nickel-based material, and alloy material.
Further, other portions of the secondary battery, the battery module, the battery pack, and the electric device of the present application will be described below with reference to the drawings as appropriate.
In one embodiment of the present application, a secondary battery is provided.
In general, a secondary battery includes a positive electrode tab, a negative electrode tab, an electrolyte, and a separator. During the charge and discharge of the battery, active ions are inserted and extracted back and forth between the positive electrode plate and the negative electrode plate. The electrolyte plays a role in ion conduction between the positive electrode plate and the negative electrode plate. The isolating film is arranged between the positive pole piece and the negative pole piece, and mainly plays a role in preventing the positive pole piece and the negative pole piece from being short-circuited, and meanwhile ions can pass through the isolating film. Each constituent element of the secondary battery is described in detail below.
[ Positive electrode sheet ]
The positive pole piece comprises a positive current collector and a positive film layer arranged on at least one surface of the positive current collector, wherein the positive film layer comprises the positive active material of the first aspect of the application.
As an example, the positive electrode current collector has two surfaces opposing in its own thickness direction, and the positive electrode film layer is provided on either one or both of the two surfaces opposing the positive electrode current collector.
In some embodiments, the positive current collector may employ a metal foil or a composite current collector. For example, as the metal foil, aluminum foil may be used. The composite current collector may include a polymeric material base layer and a metal layer formed on at least one surface of the polymeric material base layer. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel alloy, titanium alloy, silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), PET, PBT, polystyrene (PS), polyethylene (PE), etc.).
In some embodiments, the positive electrode active material may employ a positive electrode active material for a battery, which is well known in the art. As an example, the positive electrode active material may include at least one of the following materials: olivine structured lithium-containing phosphates, lithium transition metal oxides and their respective modified compounds. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery positive electrode active material may be used. These positive electrode active materials may be used alone or in combination of two or more. Wherein lithium is too muchExamples of transition metal oxides may include, but are not limited to, lithium cobalt oxide (e.g., liCoO) 2 ) Lithium nickel oxide (e.g. LiNiO) 2 ) Lithium manganese oxide (e.g. LiMnO 2 、LiMn 2 O 4 ) Lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (e.g., liNi) 1/3 Co 1/3 Mn 1/3 O 2 (also referred to as NCM) 333 )、LiNi 0.5 Co 0.2 Mn 0.3 O 2 (also referred to as NCM) 523 )、LiNi 0.5 Co 0.25 Mn 0.25 O 2 (also referred to as NCM) 211 )、LiNi 0.6 Co 0.2 Mn 0.2 O 2 (also referred to as NCM) 622 )、LiNi 0.8 Co 0.1 Mn 0.1 O 2 (also referred to as NCM) 811 ) Lithium nickel cobalt aluminum oxide (e.g. LiNi 0.85 Co 0.15 Al 0.05 O 2 ) And at least one of its modified compounds and the like. Examples of olivine structured lithium-containing phosphates may include, but are not limited to, lithium iron phosphate (e.g., liFePO 4 (also abbreviated as LFP)), composite material of lithium iron phosphate and carbon, and manganese lithium phosphate (such as LiMnPO) 4 ) At least one of a composite material of lithium manganese phosphate and carbon, and a composite material of lithium manganese phosphate and carbon.
In some embodiments, the positive electrode film layer further optionally includes a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluoroacrylate resin.
In some embodiments, the positive electrode film layer further optionally includes a conductive agent. As an example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
In some embodiments, the positive electrode sheet may be prepared by: dispersing the above components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components, in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; and (3) coating the positive electrode slurry on a positive electrode current collector, and obtaining a positive electrode plate after the procedures of drying, cold pressing and the like.
[ negative electrode sheet ]
The negative electrode sheet is detailed in the foregoing.
[ electrolyte ]
The electrolyte plays a role in ion conduction between the positive electrode plate and the negative electrode plate. The type of electrolyte is not particularly limited in this application, and may be selected according to the need. For example, the electrolyte may be liquid, gel, or all solid.
In some embodiments, the electrolyte is an electrolyte. The electrolyte includes an electrolyte salt and a solvent.
In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis-fluorosulfonyl imide, lithium bis-trifluoromethanesulfonyl imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalato borate, lithium difluorodioxaato phosphate, and lithium tetrafluorooxalato phosphate.
In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, methylethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1, 4-butyrolactone, sulfolane, dimethyl sulfone, methyl sulfone, and diethyl sulfone.
In some embodiments, the electrolyte includes an additive. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives capable of improving certain properties of the battery, such as additives that improve the overcharge performance of the battery, additives that improve the high or low temperature performance of the battery, and the like. In this application, the electrolyte includes a fluorine-containing additive that is a fluorine-containing ester monocyclic compound.
[ isolation Membrane ]
In some embodiments, a separator is further included in the secondary battery. The type of the separator is not particularly limited, and any known porous separator having good chemical stability and mechanical stability may be used.
In some embodiments, the material of the isolating film may be at least one selected from glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The separator may be a single-layer film or a multilayer composite film, and is not particularly limited. When the separator is a multilayer composite film, the materials of the respective layers may be the same or different, and are not particularly limited.
In some embodiments, the positive electrode tab, the negative electrode tab, and the separator may be manufactured into an electrode assembly through a winding process or a lamination process.
In some embodiments, the secondary battery may include an outer package. The outer package may be used to encapsulate the electrode assembly and electrolyte described above.
In some embodiments, the outer package of the secondary battery may be a hard case, such as a hard plastic case, an aluminum case, a steel case, or the like. The exterior package of the secondary battery may also be a pouch type pouch, for example. The material of the flexible bag may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, and polybutylene succinate.
The shape of the secondary battery is not particularly limited in the present application, and may be cylindrical, square, or any other shape. For example, fig. 2 is a secondary battery 5 of a square structure as one example.
In some embodiments, referring to fig. 3, the outer package may include a housing 51 and a cover 53. The housing 51 may include a bottom plate and a side plate connected to the bottom plate, where the bottom plate and the side plate enclose a receiving chamber. The housing 51 has an opening communicating with the accommodation chamber, and the cover plate 53 can be provided to cover the opening to close the accommodation chamber. The positive electrode tab, the negative electrode tab, and the separator may be formed into the electrode assembly 52 through a winding process or a lamination process. The electrode assembly 52 is enclosed in the accommodating chamber. The electrolyte is impregnated in the electrode assembly 52. The number of electrode assemblies 52 included in the secondary battery 5 may be one or more, and those skilled in the art may select according to specific practical requirements.
In some embodiments, the secondary batteries may be assembled into a battery module, and the number of secondary batteries included in the battery module may be one or more, and the specific number may be selected by one skilled in the art according to the application and capacity of the battery module.
Fig. 4 is a battery module 4 as an example. Referring to fig. 4, in the battery module 4, a plurality of secondary batteries 5 may be sequentially arranged in the longitudinal direction of the battery module 4. Of course, the arrangement may be performed in any other way. The plurality of secondary batteries 5 may be further fixed by fasteners.
Alternatively, the battery module 4 may further include a case having an accommodating space in which the plurality of secondary batteries 5 are accommodated.
In some embodiments, the above battery modules may be further assembled into a battery pack, and the number of battery modules included in the battery pack may be one or more, and a specific number may be selected by those skilled in the art according to the application and capacity of the battery pack.
Fig. 5 and 6 are battery packs 1 as an example. Referring to fig. 5 and 6, a battery case and a plurality of battery modules 4 disposed in the battery case may be included in the battery pack 1. The battery box includes an upper box body 2 and a lower box body 3, and the upper box body 2 can be covered on the lower box body 3 and forms a closed space for accommodating the battery module 4. The plurality of battery modules 4 may be arranged in the battery box in any manner.
In addition, the application also provides an electric device, which comprises at least one of the secondary battery, the battery module or the battery pack. The secondary battery, the battery module, or the battery pack may be used as a power source of the power consumption device, and may also be used as an energy storage unit of the power consumption device. The power utilization device may include mobile devices (e.g., cell phones, notebook computers, etc.), electric vehicles (e.g., electric-only vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but is not limited thereto.
As the electricity consumption device, a secondary battery, a battery module, or a battery pack may be selected according to the use requirements thereof.
Fig. 7 is an electrical device as an example. The electric device is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle or the like. In order to meet the high power and high energy density requirements of the secondary battery by the power consumption device, a battery pack or a battery module may be employed.
As another example, the device may be a cell phone, tablet computer, notebook computer, or the like. The device is generally required to be light and thin, and a secondary battery can be used as a power source.
Examples
Hereinafter, embodiments of the present application are described. The embodiments described below are exemplary only for the purpose of illustrating the present application and are not to be construed as limiting the present application. The examples are not to be construed as limiting the specific techniques or conditions described in the literature in this field or as per the specifications of the product. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.
Example 1
(1) Preparation of coating slurry
Dispersing particles of an antimony simple substance, carbon black serving as a conductive agent, styrene-butadiene rubber (SBR) serving as a binder and sodium carboxymethylcellulose (CMC) in deionized water, and fully stirring and uniformly mixing to form coating slurry.
(2) Preparation of negative electrode plate
And (3) coating the coating slurry on the surface of the prepared negative electrode plate with the active material layer of graphite in a gravure coating mode, and drying and cold pressing to obtain the negative electrode plate. The physical properties of the negative electrode sheet are shown in table 1 below.
(3) Preparation of secondary battery
And (3) fully stirring and uniformly mixing lithium manganese phosphate serving as a positive electrode material, acetylene black serving as a conductive agent and polyvinylidene fluoride (PVDF) serving as a binder in an N-methylpyrrolidone solvent system according to a weight ratio of 94:3:3, coating the mixture on an aluminum foil, drying and cold pressing to obtain the positive electrode plate.
A porous polymer film made of Polyethylene (PE) was used as a separator.
And sequentially overlapping the positive plate, the isolating film and the negative plate, so that the isolating film is positioned between the positive electrode and the negative electrode to play a role in isolation, and winding to obtain the bare cell.
The electrolyte is fluoroethylene carbonate (FEC)/(ethylene carbonate (EC) +diethyl carbonate (DEC)) (mass ratio 5:95), and the volume ratio of EC to DEC is 1:1.
And placing the bare cell in an outer package, injecting the electrolyte and packaging to obtain the secondary battery.
Examples 2 to 3
Secondary batteries of examples 2 to 3 were produced in the same manner as in example 1, except that the coating amount of the coating slurry was adjusted to change the coating thickness as shown in table 1 below.
Example 4
A secondary battery of example 4 was produced in the same manner as in example 1, except that the coating amount of the coating paste was adjusted to change the coating thickness, and the addition amount of FEC was adjusted, as shown in table 1 below.
Example 5
A secondary battery of example 5 was produced in the same manner as in example 1, except that FEC was replaced with phenyl trifluoroacetate as shown in table 1 below.
Examples 6 to 7
Secondary batteries of examples 6 to 7 were produced in the same manner as in example 1, except that FEC was replaced with phenyl trifluoroacetate and the addition amount thereof was adjusted as shown in table 1 below.
Example 8
A secondary battery of example 8 was produced in the same manner as in example 1, except that the particles of elemental antimony in the raw material were replaced with particles of antimony trioxide as shown in table 1 below.
Example 9
A secondary battery of example 9 was produced in the same manner as in example 1, except that the particles of elemental antimony in the raw material were replaced with particles of antimony trifluoride as shown in table 1 below.
Example 10
A secondary battery of example 10 was produced in the same manner as in example 1, except that the volume average particle diameter Dv50 of the particles of elemental antimony in the raw material was adjusted as shown in table 1 below.
Example 11
A secondary battery of example 11 was produced in the same manner as in example 1, except that the coating amount of the coating paste was adjusted to change the coating thickness, and the addition amount of FEC was adjusted, as shown in table 1 below.
Comparative example 1
A secondary battery of comparative example 1 was prepared in the same manner as in example 1, except that no coating layer was provided on the surface of the active material layer as shown in table 1 below.
Comparative example 2
A secondary battery of comparative example 2 was prepared in the same manner as in example 1, except that FEC was not added to the electrolyte as shown in table 1 below.
Comparative example 3
A secondary battery of comparative example 3 was prepared in the same manner as in example 1, except that the coating amount of the coating paste was adjusted to change the coating thickness, and the addition amount of FEC was adjusted, as shown in table 1 below.
Comparative example 4
A secondary battery of comparative example 4 was produced in the same manner as in example 1, except that FEC was replaced with 2-fluoro-1-naphthol as shown in table 1 below.
Comparative example 5
A secondary battery of comparative example 5 was prepared in the same manner as in example 1, except that the coating amount of the coating paste was adjusted to change the coating thickness, and the addition amount of FEC was adjusted, as shown in table 1 below.
Next, a method of testing the secondary battery will be described.
(1) Initial capacity test
The secondary battery prepared above was charged to 4.2V at 0.33C under constant temperature of 25C, then charged to current of 0.05C or less at constant voltage of 4.2V, left standing for 5min, then discharged to 2.8V at 0.33C, and tested to obtain the initial capacity of the secondary battery.
(2) Capacity retention test
The prepared secondary battery is charged to 4.2V at 1C under the constant temperature environment of 60 ℃, then charged to the current of less than or equal to 0.05C at constant voltage of 4.2V, kept stand for 5min, then discharged to 2.8V at 1C, and circulated for 500 circles, and the capacity after 500 circles obtained by testing is divided by the initial capacity, so that the capacity retention rate is obtained.
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Table 2: results of Performance test of examples 1 to 11 and comparative examples 1 to 5
As is clear from examples 1 to 11 in table 2 above, the secondary battery of the present application has good cycle performance and service life when the kind, volume average particle diameter Dv50, thickness, mass percent of the antimony-containing particles of the negative electrode sheet coating layer, the kind, mass percent of the fluorine-containing additive in the electrolyte, and the molar ratio of the antimony-containing particles to the fluorine-containing additive in the secondary battery are all within the scope of the present application.
As is evident from the comparison of example 1 and comparative examples 1-2 in Table 2 above, the coating containing antimony element is not necessarily free from fluorine-containing additives. When no coating is added, after the secondary battery is charged, the SEI film formed on the surface of the secondary battery contains a large amount of organic components, so that the SEI film has insufficient stability, is damaged due to expansion of an anode, continuously consumes active lithium for reconstruction, and has poor cycle performance; when no fluorine-containing additive is added into the electrolyte, after the secondary battery is charged, the SEI film generated on the surface of the anode material absorbs solvent molecules in the electrolyte, so that the capacity is quickly attenuated. The secondary battery of the present application has better cycle performance than the existing secondary battery.
As is clear from the comparison of example 1 and comparative example 4 in Table 2 above, when an ester-based polycyclic compound is used as an additive, although it contains fluorine, the steric hindrance increases due to polycyclic rings, and Li is generated 3 The Sb film layer is difficult to adsorb and combine, and has no priority in adsorption over the rest of the components in the electrolyte, so that it absorbs solvent molecules in the electrolyte as well, resulting in rapid degradation of capacity, and failure to improve the cycle performance of the secondary battery.
As can be seen from the comparison of example 2 and comparative example 3, and example 3 and comparative example 5 in Table 2 above, when the molar ratio of both the antimony element and the fluorine-containing additive is outside the range of the present application, li 3 The Sb and the fluorine-containing additive cannot form a good adsorption relationship, which causes excessive loss of active ions, resulting in loss of initial capacity of the secondary battery and also cannot improve cycle performance of the secondary battery.
As is apparent from examples 3 to 4 and comparative example 3 in table 2 above, when the addition amount of the fluorine-containing additive in the secondary battery is within a proper range, the effect of improving the cycle performance can be ensured; when the additive of the fluorine-containing additive in the secondary battery is excessive, the conditions of the electrolyte system, solubility, viscosity, and the like cannot be ensured to be in a good state. Therefore, it is necessary to control the addition amount of the fluorine-containing additive within an appropriate range.
As is apparent from examples 1 to 3 in table 2 above, when the content of antimony element in the secondary battery is within a proper range, a good improvement effect on cycle performance can be ensured; when the content of antimony element in the secondary battery is too much or too little, it has some influence on the cycle performance of the secondary battery. In order to ensure that a uniform SEI film with stable structure and low consumption of active lithium can be formed on the surface of the negative electrode plate, the content of antimony element needs to be controlled within a proper range so as to ensure good improvement effect on the cycle performance of the secondary battery.
As is clear from examples 3 and 10 in table 2 above, when the volume average particle diameter Dv50 of the antimony particles in the secondary battery is excessively large, it has a certain effect on the cycle performance of the secondary battery. When the volume average particle diameter Dv of the particles is 50 hours, the number of layers of the particles in the slurry is larger, and the effective coverage area of the particles is also larger. Therefore, it is necessary to control the volume average particle diameter Dv50 of the antimony particles within a suitable range.
The present application is not limited to the above embodiment. The above embodiments are merely examples, and embodiments having substantially the same configuration and the same effects as those of the technical idea within the scope of the present application are included in the technical scope of the present application. Further, various modifications that can be made to the embodiments and other modes of combining some of the constituent elements in the embodiments, which are conceivable to those skilled in the art, are also included in the scope of the present application within the scope not departing from the gist of the present application.

Claims (15)

1. A secondary battery, characterized by comprising: the negative electrode plate and the electrolyte are prepared,
the negative electrode plate comprises a current collector, an active material layer and a coating, wherein the active material layer is positioned between the current collector and the coating, and contains at least one of graphite, hard carbon, soft carbon and lithium titanate;
the coating comprises particles containing antimony elements, wherein the particles containing the antimony elements are at least one of antimony simple substances, antimony oxides and antimony trifluoride;
the electrolyte contains lithium salt and a fluorine-containing additive, wherein the fluorine-containing additive is at least one of phenyl trifluoroacetate and allyl tri (2, 2-trifluoroethyl) carbonate;
wherein the molar ratio of the antimony element to the fluorine-containing additive is 1:30-9:1.
2. The secondary battery according to claim 1, wherein a molar ratio of the antimony element to the fluorine-containing additive is 1.5:10 to 9:10.
3. The secondary battery according to claim 1, wherein the particles containing an antimony element are at least one of elemental antimony, antimony trioxide, and antimony trifluoride.
4. The secondary battery according to claim 1, 2 or 3, wherein the volume average particle diameter Dv50 of the antimony element-containing particles is 10nm to 1000nm.
5. The secondary battery according to claim 4, wherein the volume average particle diameter Dv50 of the antimony element-containing particles is 50nm to 300nm.
6. The secondary battery according to claim 1 or 2 or 3 or 5, wherein the thickness of the coating layer is 200nm to 5000nm.
7. The secondary battery according to claim 6, wherein the thickness of the coating layer is 500nm to 3000nm.
8. The secondary battery according to claim 1 or 2 or 3 or 5 or 7, wherein the mass percentage of the coating layer is 2% to 30% based on the total mass of the coating layer and the active material layer.
9. The secondary battery according to claim 8, wherein the mass percentage of the coating layer is 5% to 20% based on 100% of the total mass of the coating layer and the active material layer.
10. The secondary battery according to claim 1 or 2 or 3 or 5 or 7 or 9, wherein the fluorine-containing additive is 0.5 to 20% by mass based on the total mass of the electrolyte.
11. The secondary battery according to claim 10, wherein the fluorine-containing additive is 2 to 10% by mass based on the total mass of the electrolyte.
12. The secondary battery according to claim 1 or 2 or 3 or 5 or 7 or 9 or 11, wherein the molar concentration of the lithium salt in the electrolyte is 0.7M to 1.5M.
13. A battery module comprising the secondary battery according to any one of claims 1 to 12.
14. A battery pack comprising the battery module of claim 13.
15. An electric device comprising at least one selected from the secondary battery according to any one of claims 1 to 12, the battery module according to claim 13, or the battery pack according to claim 14.
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